Virtually all automotive vehicles have movable and/or fixed windows in their side doors, there being a requirement for various designs of weather strip seals to seal gaps between two body panel structures, such as a window pane and a door frame.
Many automotive vehicles also have decorative trims which are pigmented to blend, match or contrast with the color of the automotive vehicle body panels, and which are often used to conceal the strip seal since most seal strips are black due to the high amounts of carbon black used for the seal material. These decorative trim need a glossy or bright finish which can withstand the harsh environmental conditions which exist on the exterior of an automotive vehicle during extreme weather conditions or during high speed travel of the vehicle.
In a known manner and as visible in FIG. 1 showing the prior art, outer belt strip seals 1 with bright bead surfaces comprise a main polymeric leg 2 which is reinforced over its whole vertical width by a metal carrier 3 having an asymmetrical substantially U-shaped cross-section. This metal carrier 3 has a first branch 3a embedded in this leg 2, which is provided on one side thereof with flocked inner sealing lips 5 and 6 for sealing to the window pane, and a second branch 3b ending with a lower outer lip 7 for sealing with the door frame.
U.S. Pat. No. 6,422,571 discloses in its FIG. 3 an outer belt strip seal obtained by coextrusion, onto and around a metal carrier, of an elastomeric material such as an EPDM for both the main part of the leg and the inner sealing lips and of an ionomer material for an upper section of the leg and forming the outer bright decorative surface of the strip seal. Contrary to instant above-referred FIG. 1, both branches of the metal carrier are embedded in the strip seal, with in particular the second branch being entirely embedded in this ionomer material.
Current designs of outer belt strip seals with a bright bead, such as the one illustrated in FIG. 1, require:
as a first solution, a separate roll formed and finished decorative strip, with a bright bead that is attached to the sealing portion of the belt, or
as a second solution illustrated in FIG. 1, a single sealing and decorative strip 1, where the embedded metal carrier 3 has an adhesive applied only to specific distinct areas 8a, 8b, 8c, 8d of the metal surface (the metal carrier 3 being said in this case to be “stripe coated” on areas 8a, 8b of its first branch 3a to which the polymeric material of the main leg 2 must adhere and further on areas 8c, 8d of its second branch 3b to which the elastomeric material of the lower lip 7 must also adhere), and afterwards this stripe coated metal carrier 3 is roll formed.
The main drawbacks of this first solution implying a two-piece design are that it is costly, involves a high amount of scrap and additional assembly time, and also an additional weight.
Concerning this second solution, the metal carrier 3, which is typically wide enough to reinforce the sealing portion 2, 5, 6 of the belt strip 1, travels through extrusion tooling where the main leg 2 and the outer sealing lip 7 are extruded onto areas 8a, 8b, 8c, 8d with the adhesive, leaving the bright decorative area exposed.
FIG. 2 shows a known manufacturing method of this strip seal 1, with the following successive steps:                a step 10 of stripe abrading the metal for the carrier 3,        a step 20 of stripe applying a primer to this abraded metal,        a step 30 of curing this metal with an applied primer,        a step 40 of stripe applying adhesive to the cured metal,        a step 50 of curing the stripe adhesive coated metal,        a step 60 of roll forming the cured stripe coated metal,        a step 70 of co-extruding the rigid and flexible polymeric materials respectively forming the main leg 2 and the sealing lips 5, 6, 7,        a step 80 of calibrating the obtained coextruded blank,        a step 90 of cooling the calibrated blank,        a step 100 of applying adhesive to the cooled blank,        a step 110 of applying a flock to both inner lips 5 and 6,        a step 120 of curing the seal with flocked inner lips 5, 6,        a step 130 of cutting off the cured seal to length, and        a step 140 of curing the cut-off seal.        
The main drawbacks of this second solution with the stripe coating operations 10 to 50 for the metal carrier 3, apart from also being costly and involving a high amount of scrap, are that these operations produce volatile organic compounds (VOC's) and require a wider stock.